hadoop-common-issues mailing list archives

[jira] Commented: (HADOOP-6297) Hadoop's support for zlib library lacks support to perform flushes (Z_SYNC_FLUSH and Z_FULL_FLUSH)

Date

Thu, 24 Feb 2011 00:45:38 GMT

[ https://issues.apache.org/jira/browse/HADOOP-6297?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12998633#comment-12998633
]
Todd Lipcon commented on HADOOP-6297:
-------------------------------------
What's the Hadoop-side use case for this functionality? ie who is the new user of the added
function call?
> Hadoop's support for zlib library lacks support to perform flushes (Z_SYNC_FLUSH and
Z_FULL_FLUSH)
> --------------------------------------------------------------------------------------------------
>
> Key: HADOOP-6297
> URL: https://issues.apache.org/jira/browse/HADOOP-6297
> Project: Hadoop Common
> Issue Type: Improvement
> Components: io
> Reporter: Kevin J. Price
> Assignee: Kevin J. Price
> Priority: Minor
> Attachments: zlibpatch-0.3.patch, zlibpatch.patch
>
>
> The zlib library supports the ability to perform two types of flushes when deflating
data. It can perform both a Z_SYNC_FLUSH, which forces all input to be written as output and
byte-aligned and resets the Huffman coding, and it also supports a Z_FULL_FLUSH, which does
the same thing but additionally resets the compression dictionary. The Hadoop wrapper for
the zlib library does not support either of these two methods.
> Adding support should be fairly trivial. An additional deflate method that takes a fourth
"flush" parameter, and a modification to the native c code to accept this fourth parameter
and pass it along to the zlib library. I can submit a patch for this if desired.
> It should be noted that the native SUN Java API is likewise missing this functionality,
as has been noted for over a decade here: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4206909
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